Our P42 has two Jabsco electric heads that draw sea water for flushing into one 26 gallon holding tank. The power panel has one circuit breaker for both heads and another circuit breaker for the overboard macerator pump. Each head has a through hull for sea water flushing. The head uses a combo pump and macerator motor to bring sea water in for flushing and a macerator for chewing up the material on its way to the holding tank during the flushing operation.

Each head has an electrically operated anti siphon solenoid valve; the aft head solenoid is located in the engine compartment and the forward head solenoid is located inside a small compartment forward of the main cabin cabinets starboard side. These help to prevent water from siphoning into the bowl after flushing since both the heads and holding tank are below the waterline.

The holding tank on our boat is located beneath the main cabin sole starboard side by the setee. The through hull seacock for the macerator pump is located on the forward side of the holding tank. A small sole compartment hatch on the starboard side next to the compression post is where we have two seacocks; one for the forward cabin head sea water intake and the other for the holding tank macerator pump. Our macerator draws from the tank via a wye valve arrangement.

When its time for use I first open the through hull, turn on the head switch and activate the flush button to bring in some sea water to the bowl. When ready I hold the flush button down for at least five full seconds to allow enough time for the bowl contents to reach the holding tank. I return everything to their normal position when done.

If our tank is close to full, there is no pump out facility nearby and were in a legal place to discharge overboard I will open the macerator pump through hull and activate the macerator circuit breaker until the tank is empty. The pump sound will change to a slightly higher but distinctive pitch at that point. Close all through hulls when done. Sea water will slowly seep back into the holding tank if left open.